Process for the production of perfectly spherical culture pearls



Patented Mar. 1, 1932 UNITED STATES KOKICI-II MIKIMOTO, OF KYOBASHLK U,TOKYO-SKI, JAPAN PROCESS FOR THE PRODUCTION OF PERFECTLY SPHER-ICALCULTURE PEARLS No Drawing.

This invention relates to improvements in the process for the productionof culture pearls and has for its object to provide an improved processwhereby perfectly spherical culture pearls can be obtained.

In the culture pearl production, one process of causing a nucleus tobecome covered by layers of nacreous substance is known. This knownprocess consists in covering the nucleus, for need of a very smoothsurface, with single layer of a slightly stretched piece of the mantleof a living pearl-oyster, by binding the closing end with a draw string,cutting away the surplus part of the mantle piece to cover the wholesurface of the nucleus, and at the same time removing the draw string.It is thus ensured that the nucleus will be kept covered over its wholesurface with the mantle piece without the use of any draw string due tothe contractibility of the mantle. The nucleus is then forcibly insertedinto a suitable location in the anatomy of the mantle of another livingpearl-oyster for causing the culture of the pearl through a slight cutpurposely formed thereon.

In general, the mantle of the living pearloyster is too stout and of toogreat contractibility to cover the nucleus over its whole surface so asnot to form any wrinkle without ca danger of damaging the mantle onstretching. It is very difficult, therefore, to obtain beautiful culturepearls having smooth surface, because of the presence of the wrinkles onthe mantle cover of the nucleus. Further- 1-;5 more, the cut end of thesurplus part of the mantle cover will tend to open somewhat due to thegreat contractibility of the mantle if the surplus part is entirely cutaway. In or-- der to avoid this disadvantage, the surplus 40 part of themantle cover is required to be cut away so as to reserve some margin. Itis very difficult, however, to reserve the margin just enough not toform any opening, so that some surplus margin may be occasionallyoverpreserved, which will cause the produced culture pearl to presentsome protuberance on its surface.

. This invention is intended to eliminate the aforesaid disadvantages bythe use of anu- "10 cleus having a less smooth or coarse surfaceApplication filed May 14,

1931. Serial No. 537,507.

instead of the very smooth surface, and less stout or pliable mantle ofrelatively poor contractibility instead of the great contractibil- 'itygenerally in use heretofore. This nucleus can be obtained frompearl-oysters specially cultured for that purpose as hereinafterdescribed in detail, or from those which have being found, thoughthesurplus part of the covering mantle is cut away without preservingany margin for providmg against the tendency of a spot being uncoveredat the cut end of the surplus part of the covering mantle, the coarsesurface of the nucleus serving to ensure the close contact with themantle cover. Consequently a perfectly spherical culture pearlcorresponding to a spherical nucleus can be produced.

To specially culture the pearl-oysters so that their mantles becometransparent and pliable, the pearl-oysters are kept in a basketsuspended in deep water, which basket is constructed to exclude the sunas far as possible whilst a water circulation is permitted there- 1n.

In my process, a valve of the shell of the living pearl-oyster, havingthe transparent and pliable mantle as above described, is removed fromanother valve to expose the animal with the mantle cover, the abductorbeing separated from the removing valve by means of a knife or the likeinserted between the shell and the animal through a slightly openedcrevice between the two valves. The nucleus of the coarse surface isthen put on the mantle which is slightly contracted at that time. Thenucleus is then covered by the mantle by gently stretching the same, andis bound at the closing end with a draw string or like, keeping themantle in the stretched condition. After some time, the surplus part ofthe mantle covering the nucleus is cut away, the draw string beingremoved at the same time, since the nucleus will be kept completelycovered by the mantle without any draw string due to the constrictiveaction of the mantle. The wrinkles of the mantle cover are thensatisfactorily smoothed out. The mantle-covered nucleus thus provided isfor- 5 cibly inserted into a .suitable location in the anatomy of themantle of another living pearl-oyster for the culture of the pearl theinsertion being made through a suitable cut purposely formed at themantle by suitably m opening the valves at one end. The livingpearl-oyster bearing the mantle-covered nucleus forcibly inserted intothe mantle will be kept in water, and thereby the perfectly sphericalculture pearl will be produced. 5 Having now particularly described andascertained the nature of my said invention .and in What manner the sameis to be performed, I claim:

In culture pearlproduction, a process com- 20 prising covering a nucleusof suitably coarse surface by single layer of a piece of the pliable andrelatively poor contractive mantle of a living pearl-oyster which isspecially cultured or which has not been spawned long, 25 by binding theclosing end with a drawstring, cutting away the Whole surplus part ofthe mantle cover, and simultaneously removing away the draw string atthe same time, and inserting the mantle-covered nu- 30 cleus intosuitable location in the anatomy of the mantle of another livingpearl-oyster, for culturing the pearl against its contractibility.

In testimony whereof I have signed my name to this specification.

KOKIGHI MIKIMOTO.

